Google has already gathered several patents in relation to Project Glass. These patents range from displaying sound notifications to a trackpad to projecting a virtual keyboard. Google has now also gained a patent for letting a device track where your eye is really looking at.
Google already has a patent for augmenting the field of view of a user by overlaying additional information on what is currently being viewed. But this method depends more on the general direction and orientation of the user's head and the device rather than what the user is actually looking at.
The method described in the new patent is more subtle and potentially more powerful. It describes how cameras will be tracking the eyes to determine what exactly the user is gazing at, as well as other related properties. For example, it can measure the dilation of the pupil of the eyes to infer the user's emotional state or response to an object. It can also measure how long a user is looking at an object, something that advertisers can potentially exploit.
Features described in this new patent probably won't make it into the current iteration of Google Glass, especially if new hardware needs to be added to make it work. However, Google has also been granted a patent for a new type of near-to-eye display that could hint at a new version of Glass hardware in the future.